Intention to examine metaphysics of stoic philosophical schools faces number of obstacles. Metaphysics was attractive to the most ancient of stoics, i.e. Zenon, Chrysippus and Cleanthes whose philosophical works were lost and none of them survived until now. Their philosophical teaching is available to us only via secondary sources whose authors are usually very hostile to stoic philosophy. The teachings of these authors also differentiated in some aspects and philosophy of the stoic school itself underwent some development and changes that are difficult to interpret on the basis of secondary sources only. Being aware of these difficulties we try to provide an overview of the fundamental structure of stoic metaphysics developed in the most ancient stage of stoic thought while paying attention to the most problematic questions. We start our analysis with the concept of body and reconstruction of three-level stoic metaphysics and the most universal stoic category „something“. Then we proceed with active and passive principles of body and relevant parts of the stoic metaphysical system.